Vehicle disk brake

ABSTRACT

A disk-brake unit which has an unusual ability to operate safely as well as a simple construction and which is intended to be fitted in vehicles, comprises a caliper body extending astride a braking disk, at least one pair of pads facing the disk on opposite sides and restrained on the caliper body by suspension on a pin, each pad having a support plate for a friction lining, and stop means formed in the plates and facing respective complementary stop means formed in the caliper body for restraining the pads in a direction tangential to the disk, the unit further comprising between the pin and the at least one pair of pads, a single element for constantly maintaining the suspension of the pads on the pin and simultaneously constantly urging each pad both towards the complementary stop means and away from the braking disk.

BACKGROUND OF THE INVENTION

[0001] The subject of the present invention is a disk brake unit.

[0002] In particular, the present invention relates to a disk brake unitcomprising a caliper body extending astride a braking disk, at least onepair of pads facing the disk on opposite sides and restrained on thecaliper body by suspension on a pin, each pad having a support plate fora friction lining, as well as stop means formed in the plates and facingrespective complementary stop means formed in the caliper body forrestraining the pads in a direction tangential to the disk.

[0003] As is known, in disk brake units of the type indicated above, theneed arises to limit as far as possible the braking noise which oftentakes the form of a particularly annoying whistle.

[0004] This phenomenon is attributed to vibration of the pads arisingduring braking.

[0005] A method of the prior art for preventing this problem proposesthat the disk brake unit of the type specified above comprise, inaddition to a spring acting between the caliper body and the pads inorder to move them away from the braking disk, a spring mounted on eachplate, and acting between the caliper body and the plate, in orderconstantly to urge the stop means provided in the plates towards thecomplementary stop means provided in the caliper body.

[0006] However, it should be borne in mind that this spring makes theconstruction of the disk brake unit particularly complex.

[0007] In fact, it is essential to provide suitable seats in the platesfor housing the springs, as well as means for fixing the springs.

[0008] Moreover, because of the provision of the spring as proposed inthe prior art, the assembly of the disk brake unit, as well asoperations to replace the pads or the disk, or the disk and wheelassembly in motorcycling applications, are particularly laborious.

[0009] In fact, it must be borne in mind that the above-mentioned springnecessitates predefined assembly and dismantling operations which arepoorly suited to maintenance situations.

[0010] The provision of these springs complicates operations to fit thedisk brake unit or to replace the pads to an extent such as to preventtheir use in disk brake units intended for racing vehicles.

SUMMARY OF THE INVENTION

[0011] The problem upon which the present invention is based is that ofproposing a disk brake unit which has structural and functionalcharacteristics such as to overcome the disadvantages mentioned abovewith reference to the prior art.

[0012] This problem is solved by means of a disk brake unit of the typespecified above, characterized in that it comprises, between the pin andthe at least one pair of pads, a single element for constantlymaintaining the suspension on the pin and simultaneously constantlyurging each pad both towards the complementary stop means and away fromthe braking disk.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0013] Further characteristics and the advantages of the disk brake unitaccording to the invention will become clear from the followingdescription of preferred embodiments thereof, given by way ofnon-limiting example, with reference to the appended drawings, in which:

[0014]FIG. 1 is a view of a disk brake unit according to the invention,from above,

[0015]FIG. 2 is a section through the disk brake unit of FIG. 1, takenon the line II-II,

[0016]FIG. 3 shows the detail of the disk brake unit of FIG. 1 indicatedby the arrow III, on an enlarged scale,

[0017]FIG. 4 shows the detail indicated by the arrow IV of the diskbrake unit of FIG. 2, on an enlarged scale,

[0018]FIG. 5 is a view of a component of the disk brake unit of FIG. 1from above,

[0019]FIG. 6 shows the detail of FIG. 5, viewed along the arrow VI,

[0020]FIG. 7 shows the detail of FIG. 5, viewed along the arrow VII,

[0021]FIG. 8 is a view of a second component of the disk brake unit ofFIG. 1, from above,

[0022]FIG. 9 shows the detail of FIG. 8, viewed along the arrow IX,

[0023]FIG. 10 is a view of a third component of the disk brake unit ofFIG. 1, from above,

[0024]FIG. 11 is a view of a disk brake unit according to a secondembodiment of the invention, from above,

[0025]FIG. 12 is a section through the disk brake unit of FIG. 11, takenon the line XII-XII,

[0026]FIG. 13 shows the detail of the disk brake unit of FIG. 11indicated by the arrow XIII, on an enlarged scale,

[0027]FIG. 14 shows the detail of the brake unit of FIG. 12 indicated bythe arrow XIV, on an enlarged scale,

[0028]FIG. 15 is a view of a component of the disk brake unit of FIG.11, from above,

[0029]FIG. 16 shows the detail of FIG. 15, viewed along the arrow XVI,

[0030]FIG. 17 shows the detail of FIG. 15, viewed along the arrow XVII,

[0031]FIG. 18 is a view of a disk brake unit according to a thirdembodiment of the invention, from above,

[0032]FIG. 19 is a section through the disk brake unit of FIG. 18, takenon the line XIX-XIX,

[0033]FIG. 20 shows the detail of the brake unit of FIG. 18 indicated bythe arrow XX, on an enlarged scale,

[0034]FIG. 21 shows the detail of the brake unit of FIG. 19 indicated bythe arrow XXI, on an enlarged scale,

[0035]FIG. 22 is a view of the brake unit of FIG. 18 from above, in afurther stage of operation,

[0036]FIG. 23 shows the detail of the brake unit of FIG. 11 indicated bythe arrow XXIII, on an enlarged scale,

[0037]FIG. 24 shows a component of the disk brake unit of FIGS. 18 and22, from above,

[0038]FIG. 25 shows the detail of FIG. 24 viewed along the arrow XXV.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] With reference to the drawings, a disk brake unit according tothe present invention is generally indicated 1. In particular, in theembodiment described, reference will be made to a disk brake unit of thetype with a fixed caliper for braking a conventional motor-vehiclewheel, not shown.

[0040] The disk brake unit 1 comprises a caliper body 2 connected to aconventional support which is intended to be fixed rigidly to a portionof the wheel suspension. The caliper body 2 extends astride a brakingdisk 3, of which the view shown schematically in FIGS. 1 and 2 islimited to a peripheral portion or braking band. The disk 3 is alsofixed to the wheel in a conventional manner, not shown.

[0041] It should also be noted that, in normal conditions of forwardmovement of the motor vehicle, the braking band of the disk 3 movesthrough the disk brake unit 1, following an arcuate path, indicated bythe arrow “F” (FIGS. 1 and 2). An upstream portion “I” and a downstreamportion “O” are defined in the disk brake unit 1, with respect to thisdirection of movement. In the following description, any reference to“upstream” and “downstream” portions should be understood, as specifiedabove, with reference to the above-mentioned direction of movement ofthe braking band through the brake unit 1. The direction identified bythe above-mentioned arrow “F” is defined as a direction tangential tothe disk. Reference will also be made below to portions or components ofthe brake unit which are disposed “above” or “outside the disk”, meaningthe portions or components which are disposed on the side of the unitindicated by the arrow “U” of FIG. 2. Similarly, reference will be madebelow to portions or components of the brake unit which are disposed“below” or “on the disk side”, meaning the portions or components whichare disposed on the side of the unit indicated by the arrow “D” of FIG.2.

[0042] The caliper body 2 comprises, integrally, an outer caliperhalf-body 4 and an inner caliper half-body 5, positioned on oppositesides of the braking band of the disk 3. At least two single-actingpistons 6 are guided for sliding in hydraulic braking cylinders disposedfacing one another and formed integrally within the half-bodies 4 and 5.Bridge portions 7 extending parallel to the axis X-X of rotation of thedisk 3 interconnect the two half-bodies 4 and 5.

[0043] The disk brake unit 1 comprises at least one pair of identicaland opposed pads 8 and 9 mounted on the caliper body 2 on opposite sidesof the disk 3 and between the pistons 6. The pads 8, 9 compriserespective support plates 10 and 11 for supporting correspondingfriction linings 12 and 13. In particular, the friction linings 12, 13are fixed, in conventional manner, on respective faces or supportsurfaces 14 and 15 of the plates. The pads are mounted in the caliperbody 2 with the corresponding friction linings 12 and 13 facing towardsthe disk 3 so that opposite faces or thrust surfaces 16 and 17 of theplates face towards the pistons 6. The plates have corresponding upperlug extensions or lugs 18 and 19 extending through a window 20 formed inan upper portion of the caliper body 2 between the half-bodies 4 and 5.The lugs have respective through-holes or slots 21 and 22. In each pad,the lug is advantageously provided in a substantially central positionrelative to the longitudinal dimension of the pad. In the workingposition, the slot in the lug is disposed above the disk or, in otherwords, outside the disk so that it is above the region in which thepistons act (FIGS. 2, 8 and 9).

[0044] A pin 23 has a central portion of predominant length extendingthrough the caliper body 2, through the window 20. The pin 23 is engagedthrough the slots 21 and 22 with clearance such that it secures the padsto the caliper body whilst allowing them to slide freely axiallyrelative to the pin. In other words, the pin acts as a guide for thepads during the movement towards and away from the disk. The pin 23 hasa tip end 24 and a head end 25 in guided engagement in the caliper body2 on the sides on which the half-bodies 4 and 5 are disposed,respectively. The head end 25 is housed in abutment in a seat 26 formedin one half-body 4. A portion of the pin which is disposed far enoughalong the axis of the pin from the head end to project from thehalf-body 4 housing the head end 25, on the opposite side to the headend 25, has a seat for means for fixing the pin axially such as, forexample, a transverse through-hole 27 in the pin for housing a split pin28. The split pin 28 may have a portion projecting from the window 20and bent against an upper surface 29 of the half-body 4 so as to preventrotation of the pin 23 (FIGS. 1 and 10).

[0045] Each plate 10 (11) has, on opposite sides, lateral shoulders 30and 31 constituting stop means for cooperating with facing firstcomplementary stop means 32 formed in the downstream portion “O” of thecaliper body 2 and second complementary stop means 33 formed in theupstream portion “I” of the caliper body 2. Both the first and thesecond complementary stop means are arranged tangentially relative tothe disk. In the embodiment described, these first and secondcomplementary stop means 32, 33 comprise opposed abutment surfacesdefining laterally notches or grooves or, in other words, seats providedin the half-bodies 4 and 5 in positions facing the pistons 6.

[0046] The disk brake unit 1 also comprises a single element, generallyindicated 34, disposed between the pin 23 and the at least one pair ofpads in order to keep the pads constantly suspended on the pin andsimultaneously to urge each pad constantly both towards the firstcomplementary stop means 32 and away from the braking disk 3 (FIGS. 1,2, 5, 6 and 7).

[0047] The single element advantageously comprises first portions 35 forurging the pads 8 and 9 away from the braking disk 3 and at the sametime, for constantly maintaining the suspension on the pin 23. The term“maintaining the suspension” is intended to define an action whichaffects the pads 8, 9 and, in particular, the friction linings 12, 13,urging them away from the pin 23, towards the disk 3 so as to bring thepin 23 into abutment with the upper portion of the surface defining theslot 21 (22) formed in the lug 18 (19).

[0048] With further advantage, the single element 34 comprises secondportions 36 for urging the pads 8, 9 towards the first complementarystop means 32. In other words, the single element 34 constantly urgesthe pads 8, 9 in the tangential direction “F” of the forward movement ofthe motor vehicle in a manner such that, upon braking, when the padscome into contact with the disk, the preloading provided by the singleelement prevents vibrations from arising, also facilitating thecommencement of braking since the play between the plates and the padseats in the caliper body is fully taken up by the single element, evenbefore the braking action starts.

[0049] According to one embodiment, the single element 34 is a wirespring, for example, made of steel spring wire.

[0050] A configuration of the wire spring which ensures the desiredsimultaneous actions on the pads 8, 9 is a substantially “M”-shapedconfiguration which has two limbs constituting the first portions 35 andhaving first arms 37 and second arms 38 extending in different planes,as well as bent free ends constituting the second portions 36. The firstand second arms are connected to one another by respective elbowportions 39.

[0051] Each second arm advantageously has a curved portion 42 shapedlike a leaf spring. This portion bears against the pad with at least twoend portions 43 and 44 of the second arm 38 and against the pin 23 withan intermediate portion 45. The leaf-spring-shaped curved portion 42thus preloads the suspension of the pad on the pin, ensuring that,during the vibrational stresses which occur before and during braking,accidental stresses on the pad tending to lift or move the pad away fromits working position facing the braking band of the disk are balanced bythe constant action of the leaf-spring-shaped curved portion. In otherwords, this curved portion 42 can move the friction lining 12 (13) awayform the pin 23 (arrow “P” of FIG. 4).

[0052] The spring 34 also comprises hook-shaped bent end portions 46 forurging the pads 8, 9 (in the direction of the arrow “T”) towards thecomplementary stop means 32, in a direction tangential to the disk. Thehook-shaped portions 46 are advantageously arranged astride the upperedge of the plate 10 (11), so as to abut the outer surface defining thelug-like extension 18 (19) and, in particular, to abut portions 47 ofthe lug which extend substantially radially relative to the disk 3. Thehook-shaped portions 46 preferably have parts 48 which are disposedsubstantially transversely relative to the plates and which can engagethe edge 47 the plate. With further advantage, the free end 49 of thehook 46 is bent onto the plate 10 (11) externally or, in other words,against the face 17 of the plate remote from the disk and facing thepistons 6 (FIGS. 4 and 5).

[0053] To ensure the correct arrangement of the wire spring 34 betweenthe pin 23 and the pads 8, 9, the spring comprises a coiled portion 40which is fitted on the pin 23. A portion constituting a mounting lever41 extends from the top of the coil.

[0054] For a better understanding of the invention and appreciation ofits advantages, the main steps of the assembly of the disk brake unit 1are described below.

[0055] First of all, the pair of pads 8, 9 is inserted through thewindow 20 in-the caliper body 2 so that each pad is housed in therespective seat defined laterally by the complementary stop means 32 and33. This operation is facilitated by the provision of a temporarysupport surface 50 which is disposed in the half-bodies 4, 5 below thepistons 6 and which does not have the function of reacting to thebraking forces but has the sole purpose of keeping the pads in thecorrect position during the assembly operations.

[0056] The wire spring 34 is then brought alongside the pads, passingthrough the window 20. During the insertion of the spring through thewindow 20 and between the pads, it will be necessary to move the limbs35 towards' each other so that the distance between them is less thanthe distance between the plates 10, 11 of the pads. When the limbs 35 ofthe spring are released, portions of the second arms 38 abut the pads.In particular, the second arms abut a connecting region 51 between thesupport plates 10, 11 and the friction linings 12, 13 of the pads.

[0057] During the insertion of the wire spring through the window untilit abuts the pads, it is necessary to pay particular attention to itsorientation relative to the caliper body and to the direction of forwardmovement of the vehicle. In particular, the wire spring must be orientedin a manner such that its hook-shaped ends 46 face the upstream portion“I” of the caliper body.

[0058] The pin 23 is then inserted. In order to insert the pin, it isnecessary first of all to press the spring 34 towards the pads and atthe same time towards the downstream portion “O” of the caliper body, bymeans of the mounting lever 41, until the eye defined by the coil-shapedportion 40 of the spring is aligned with the slots 21, 22 in the platesand the seats provided for the pin in the half-bodies 4, 5. During theinsertion of the pin, the pads are lifted from the temporary supportsurfaces 50, remaining suspended on the pin 23. When the operation toinsert the pin has been completed by the abutment of the head end 25 inthe seat 26 of the half-body 4, accidental release of the pin isprevented by the insertion of the split pin 28 in the hole 27 in the pinwhich is accessible between the half-body 4 and the plate 10 (FIG. 1).

[0059] During the insertion of the pin 23, it will be necessary to forcethe intermediate portions 45 of the leaf-spring-shaped curved portions42, preloading the suspension of the pads on the pin.

[0060] As a result of the provision of the limbs 35 of the wire spring34 in abutment with the angles formed between the plates and thefriction linings, a force having a component parallel to the plane ofthe braking band of the disk in a radial direction and directed towardsthe axis of the disk, as well as a component perpendicular to that planeand directed towards the pistons housed in the caliper body can beexerted on each pad. The radial component developed by the limbs of thespring keeps the upper, inner surface of the slot in the plateconstantly in abutment with the pin, thus ensuring precise radialpositioning of the friction linings, that is, it ensures that they facethe disk perfectly in any working condition and in spite of theinevitable constructional play. The component directed towards thepistons keeps the pads constantly away from the disk and in abutmentwith the respective pistons when the brake unit is inactive. The factthat, by virtue of this transverse action of the spring relative to thedisk, the pads are kept apart and in abutment with the pistons even whenthe caliper is not astride the disk, is also particularly advantageous.In other words, the spring acts as a separator so as always to permitmounting and removal of the disk or of the caliper body in the mannerwhich will be described in greater detail below.

[0061] At the same time, the hook-shaped portions of the wire springexert a force having a component directed towards the downstream portionof the caliper body, substantially in the same direction as the brakingforce and tangential to the disk. The force exerted by the hooks thuskeeps the pads constantly in abutment with the complementary stop andbraking-force reaction means formed in the downstream portion “O” of thecaliper body, thus avoiding dead times-necessary for taking up the playbetween the pad and the caliper body, ensuring quicker braking of thevehicle every time the brake is operated. This arrangement also avoidsimpacts between the plates and the caliper body, as well as vibrationsand annoying whistles.

[0062] As can be appreciated from the foregoing description, in additionto satisfying the above-mentioned requirements, the disk brake unitaccording to the present invention requires no tools for its assemblyand the small assembly force required renders it also usable in racingequipment in which operation and maintenance times must be particularlyshort.

[0063] A further advantage of the invention lies in its unusualstructural simplicity which enables it to be produced at a very lowcost.

[0064] The fact that the wire spring enables the pads to be kept,unstressed by the pistons, outside the space occupied by the disk, evenwhen the disk is removed, is a particular advantage. For a betterappreciation of this advantage, the principal operations necessary toreplace a racing vehicle wheel provided with a disk brake disk aredescribed below.

[0065] First of all the wheel pin, and then the wheel complete with diskor disks, are removed. During this step, the calipers, which aresupported by forks, are positioned towards the outside of themotor-vehicle by virtue of the ability of the forks to pivot freelyabout their own axes so as to permit removal of the bulky wheel-rim.

[0066] The new wheel provided with the disk or disks is then inserteduntil the caliper bodies are disposed in the space between the disks andthe wheel rim. The caliper bodies are pivoted into alignment with thedisks and the fitting of the wheel is completed. During this step, thebraking bands of the disks reach their operative positions inside thecaliper body only if the pads, which are floating on their pin, do notobstruct their insertion between the half-bodies. This is provided forsafely by the above-described spring which constantly ensures that thepads are disposed in abutment with the pistons and that the necessaryspace between the half-bodies is free to receive the new disk.

[0067] Naturally, variations and/or additions may be provided for theembodiment described and illustrated above.

[0068] As an alternative to the arrangement shown in FIGS. 1 to 7, thehook of the single element 34 has a coiled portion 52. By virtue of thecoiled portion, the wire spring exerts a constant force, even in theevent of large movements of the pad (FIGS. 11 to 17).

[0069] As an alternative to the arrangement shown in FIGS. 1 to 9, alarge part of the length of the second arm 38 of each limb 35 of thespring 34 abuts the pad and the constant suspension force on the pin 23is ensured by the resilience of the elbow-like bent limb. In this case,the hook-shaped bent portion 36 and, in particular, the portion 48disposed transversely relative to the plate 10 (11) will be free toslide on the side 53 of the lug 18 (19). For this reason, the plates 10,11 will have lug-like extensions 18, 19 provided with sides 53 disposedradially and extending almost as far as the vicinity of the frictionlinings 12, 13 (FIGS. 18 to 25).

[0070] To prevent the second arms from falling between the respectivepads 8, 9 and the braking band of the disk 3 as a result of wear of thefriction lining 12, 13, a portion 54 of each second arm is in abutmentwith an upper edge 55 of the respective plate 10, 11. For example, thesecond arm has a lateral extension which extends outwardly relative tothe disk and which abuts the edge of the plate, urging it constantlyinto suspension on the pin, even if the friction linings are completelyworn out (FIGS. 22 and 23).

[0071] As an alternative to the arrangement described above, the calipermay be of the floating type and may be intended for vehicles such as,for example, motorcars, snowmobiles, motor-vehicles, motorcycles, andthe like.

[0072] A further subject of the present invention is a spare parts kitcomprising at least a pair of pads, a pin and a single element forconstantly maintaining the suspension of the pads on the pin and forconstantly urging each pad both towards complementary stop means andaway from the braking disk, as described above.

[0073] A further subject of the invention is the single element whichcan constantly maintain the suspension of the pads on a pin and whichcan constantly urge each pad both towards complementary stop means andaway from the braking disk, as described above.

[0074] In order to satisfy contingent and specific requirements, anexpert in the art may apply to the above-described preferred embodimentsof the disk-brake unit many modifications, adaptations and replacementsof elements with other functionally equivalent elements without,however, departing from the scope of the appended claims.

1. A disk-brake unit (1) comprising a caliper body (2) extending astridea braking disk (3), at least one pair of pads (8, 9) facing the disk onopposite sides, each pad having a support plate (10, 11) for a frictionlining (12, 13), and stop means (30) formed in the plates and facingrespective complementary stop means (32) formed in the caliper body forrestraining the pads in a direction tangential to the disk,characterized in that said pads (8, 9) are restrained on the caliperbody by suspension on a pin (23), and in that the unit comprises,between the pin and the at least one pair of pads, a single element (34)for constantly maintaining the suspension of the pads on the pin andsimultaneously constantly urging each pad both towards the complementarystop means and away from the braking disk.
 2. A unit according to claim1, in which the at least one pair of pads is restrained on the pin by asubstantially central portion (18, 19) of each pad.
 3. A unit accordingto claim 1 or claim 2, in which the pin is housed with clearance inslots (21, 22) provided in the central portions of the plates, theseportions being disposed outside the disk.
 4. A unit according to claim1, in which the single element comprises first portions (35) which urgethe pads away from the braking disk and constantly maintain thesuspension on the pin, as well as second portions (36) which urge thepads towards the complementary stop means.
 5. A unit according to anyone of the preceding claims, in which the single element is a wirespring (34).
 6. A unit according to claim 5, in which the wire is steelspring wire.
 7. A unit according to claim 5 or claim 6, in which thespring is substantially “M”-shaped with two limbs (35) having respectivefirst arms (37) and second arms (38) which extend in different planes,as well as respective bent free ends (36).
 8. A unit according to anyone of claims 5 to 7, in which the spring comprises a coiled portion(40) fitted on the pin.
 9. A unit according to claim 8, in which aportion constituting a mounting lever (41) extends from the coil.
 10. Aunit according to any one of claims 7 to 9, in which the second armshave portions (43, 44) abutting the pads.
 11. A unit according to claim10, in which the second arms abut respective connecting regions (51)between the support plates and the friction linings of the pads.
 12. Aunit according to claim 10 or claim 11, in which a portion (54) of eachsecond arm abuts an upper edge of the respective plate.
 13. A unitaccording to any one of claims 7 to 12, in which each second arm has acurved portion (42) shaped like a leaf spring for preloading thesuspension of the plate on the pin so as to move the friction liningaway from the pin.
 14. A unit according to any one of claims 5 to 13, inwhich the spring has hook-shaped bent end portions (46, 48) for urgingthe pads towards the complementary stop means in a tangential direction.15. A unit according to claim 14, in which the hook-shaped portions aredisposed astride the plates.
 16. A unit according to claim 15, in whichthe hook-shaped portions have parts (48) disposed substantiallytransversely relative to the plates.
 17. A unit according to any one ofclaims 14 to 16, in which the end (49) of the hook is bent onto theplate externally.
 18. A unit according to any one of claims 14 to 17, inwhich the hook has a coiled portion (52).
 19. A spare parts kitcomprising at least a pair of pads (8, 9), a pin (23), and a singleelement (34) suitable for a disk brake unit as claimed in any of claims1 to
 18. 20. A single element (34) suitable for a disk brake unit asclaimed in any one of claims 1 to 18.